Plant invasion at landscape and local scales along roadways in the mountainous region of the Greater Yellowstone Ecosystem

Abstract

Roadways are increasingly recognized as common points of entry for non-native species into natural habitats in mountainous areas. Studies were conducted within the Greater Yellowstone Ecosystem from 2003 to 2007 to evaluate (1) landscape scale patterns of non-native plant richness along roadways, and (2) local scale factors influencing native and nonnative plant richness and cover, and surrogate nonnative plant (SNP) emergence in an invaded habitat. At the landscape scale, non-native plant richness decreased with increased elevation and increased distance from the road, and was positively correlated to the proportion of plots with signs of disturbance. Non-native plant richness also varied by habitat type: sagebrush steppe had the highest and alpine the lowest. At the local scale, in sagebrush steppe, SNP emergence was negatively associated with increased distance from the road, and percent cover of litter was positively associated with SNP emergence. The proportion of non-native plant cover and richness decreased, while the proportion of native cover and native species richness increased with distance from road. Our study suggests that landscape scale variables such as elevation and habitat type influence non-native plant success, and that while local conditions adjacent to the road may be favorable for non-native plants, factors which vary at the local scale can also effect non-native plant establishment away from the roadside. This highlights the need for studies to evaluate multiple scales when assessing patterns and processes driving non-native plant invasions, and suggests that sagebrush steppe may be resistant to invasion as long as it remains undisturbed.

Annual monitoring reveals rapid upward movement of exotic plants in a montane ecosystem

“…Instead, the high variation in exotic species composition between years indicates that not all introductions are successful, while the increase in exotic richness over time shows that colonization events outnumber extinction events. Although traffic density did not increase during the sampling period, propagules are still easily moved across large distances by vehicles, road maintenance vehicles, or even cattle (Richardson et al 2000;Von der Lippe and Kowarik 2007;Pollnac et al 2012). Since the study area is a major tourist attraction as well as an important international trade route, vehicle movement is a likely propagule dispersal vector for introducing new species from distant source populations.…”

The role of railway lines in the distribution of alien plant species in the territory of Daugavpils City (Latvia)

“…These factors, reported in the literature, could be, e.g. higher levels of disturbance (Hansen & Clevenger, 2005;Pollnac et al, 2012), seed traits and certain life-history traits like seed production (Westermann et al, 2011), similarity of abiotic conditions such as type of soil and slope aspect (Gelbard & Harrison, 2003), better light (Trombulak & Frissell, 2000;Seiler, 2001;Flory & Clay, 2006) and wind conditions (Seiler, 2001;.…”

Predicting Microstegium vimineum invasion in natural plant communities of the southern Blue Ridge Mountains, USA

“…Patterns of invasion result from a combination of species' traits, propagule pressure and variation in the local environment and surrounding landscape (Eschtruth and Battles 2011;Kumar et al 2006;Lonsdale 1999). A common research finding is that invasive plant species abundance increases with human-related disturbance and movement of propagules along roads, trails and water ways (Hodkinson and Thompson 1997;Pollnac et al 2012;Von der Lippe and Kowarik 2007). Establishment rates are lower in intact natural areas (Lonsdale 1999) where disturbance and invasive propagule pressure are generally low (Eschtruth and Battles 2009b), but shade-tolerant invasives can threaten protected natural areas and have detrimental long-term impacts on intact forests (Martin et al 2009).…”